Twist caps have long been used to seal the contents of bottles prior to shipment and sale. By providing at least vestigial threads on the cap and bottle top, rotation of the cap in one direction with respect to the bottle fixedly and sealingly connects the cap to the bottle top, while rotation of the cap in the opposite direction is required to remove the cap from the bottle prior to dispensing contents of the bottle. Such a packaging system is used in a wide variety of industries for a wide variety of goods and the bottles and caps take a wide variety of forms. In the pharmaceutical industry, for example, the "bottle and cap" may be of various forms and materials and may be known by a variety of names. However, for convenience in this application, it will be understood that the terms "bottle" and "cap" are used in a broad sense and it will be understood that by a bottle with a twist cap is meant essentially in a container with a cover whose placement and removal involves a relative twisting motion. Although the present invention is usable in a variety of industries, it was developed in connection with the pharmaceutical industry and by way of convenient example will be discussed in that context.
In the pharmaceutical industry it is particularly important that the torque which must be supplied by the consumer to open a new twist cap bottle be within a defined range. More particularly, if the cap is too loose on the newly purchased bottle, there is risk of inadequate sealing of the contents of the bottle, or at least the risk of a doubt on that point by the consumer. On the other hand, if the cap is too tight on the newly purchased bottle, the consumer will have difficulty in removing it, resulting in unwanted consumer frustration and dissatisfaction. While automatic twist capping machines are controllable as to the torque applied in securing the twist cap to the bottle, the twist cap removal force may vary over time due to minor gradual changes in cap and bottle dimensions, capping machine wear or misadjustment, or a variety of other causes. Accordingly, it has been the practice, at least in the pharmaceutical industry, to test, on a sampling basis, the bottle cap removal force on completed twist capped bottles prior to packaging for shipment.
A prior bottle cap removal torque tester (torque tester), which has been in use for many years, includes a horizontal base plate on which lies a circumferentially spring biased turntable. Rotation of the turntable against the spring force correspondingly rotates an indicator needle across an analog scale located at the front end of the base plate. The turntable carries jaws threadedly adjustable toward and away from each other. The jaws are horizontally movable diametrally to the turntable. A screw rotatable diametrically the turntable engages the jaws to move same toward and away from each other. A bottle upstandingly supported on the turntable is gripped between the two jaws to hold it against rotation with respect to the turntable. An upstanding post rises from the base behind the turntable. A sleeve is axially and circumferentially movable on the post and is fixable thereto by a thumb screw extending radially through the sleeve and into engagement with the periphery of the post. The height of the sleeve on the post is set to correspond to the height of the bottle to be tested. A beam is fixed to and extends forwardly from the sleeve and on its forward end carries in a cantilevered manner a vertical tube. A vertical shaft is rotatable and vertically slidable in the vertical tube. A rubber clamping ring fits loosely around cap and is tightened around circumference of cap by a handle attached to a cam which forces a steel disc down on the confined rubber ring, forcing it tight against the side of cap. To maintain a consistent downward force, a horizontal platform is fixed to the top of the shaft for carrying manually stacked weights. A coaxial rod is upstanding from the platform and passes through central openings in the weights to prevent them from falling off the platform. A radial lever extending from the lower end of the shaft permits a person to manually rotate the shaft and hence rubber clamping ring in the loosening direction of the cap. As long as the cap remains tight on the bottle, the circumferential advancement of the lever results in corresponding circumferential advancement of the bottle and turntable against the turntable restoring spring force and hence advances the needle across the analog scale, until the restoring torque of the turntable spring exceeds the torque required to loosen the cap.
Finally, a bell crank is pivoted on the cantilevered member. The bell crank has a lift arm carrying a roller underlying the weight platform such that upward and forward swinging of that arm lifts the weight platform and hence the rubber disk upward to free the bottle. The forward end of the bell crank has a handle on it which a person can push down to thus lift the weight platform and rubber clamping ring, or can allow to pivot up and back to lower the weight platform and rubber clamping ring onto a bottle cap for testing. A downward and forward extension of the first arm engages a stop on the cantilevered beam to limit rearward pivoting of the first arm and hence limit downward movement of the weight platform and chuck with respect to the cantilevered beam.
Applicant has noted a number of sources of error and nonrepeatability and other difficulties in this prior apparatus, which the present invention seeks to overcome.
Accordingly, the objects and purposes of the present invention include the provision of:
(1) A bottle cap removal torque tester apparatus which eliminates manual rotation of the chuck and hence reduces variation in chuck rotational acceleration and velocity in tests conducted by different persons or by the same person at different times, and wherein chuck rotation is carried out electrically with precise and repeatable control of acceleration and velocity.
(2) An apparatus as aforesaid which positively engages bottle caps of a wide variety of sizes and materials without slippage, and in which rubber friction engagement between chuck and cap is eliminated.
(3) An apparatus as aforesaid in which the weight of operating portions of the apparatus enhances positive engagement of the cap, and in which repeatable vertical friction in vertical movement of the chuck toward and away from the cap so as to equalize friction in the actual down force of the chuck on the cap.
(4) An apparatus as aforesaid which senses the torque applied to the cap at a location interposed between the cap and a cap rotate motor, which can store and read out bottle cap removal force measurements and which can be made self contained and movable from place to place by use of a battery power source.
(5) An apparatus as aforesaid which is usable with a variety of shapes and sizes of bottles and which is capable of automatically centering the bottle beneath the cap engaging portion of the apparatus.
(6) An apparatus as aforesaid which is readily operable by persons with little training and relatively simple and inexpensive in structure, but provides a substantially improved reliability and repeatability in measurements.
Other objects and purposes of the invention will be apparent to person acquainted with apparatus of this general type upon reading the following specification and inspecting the accompanying drawings.